Senator Clinton defied the polls and edged out Sen. Barack Obama with the help of women voters, roaring back from defeat in Iowa and setting up an intraparty battle of historic proportions – pitting the first viable woman and African-American against each other for their party's nomination. Both well-funded and well-organized, Clinton and Senator Obama represent a clash between a seasoned, establishment-backed Washington insider and a youthful, charismatic outsider whose campaign has morphed into a movement.

In the Republican race, Senator McCain surged ahead of former Massachusetts Gov. Mitt Romney in a state that had endorsed his straight-shooting style in the 2000 primary. Left for politically dead just a few months ago, McCain now becomes a top contender for his party's nomination in a still-crowded GOP field.

"There are no front-runners in either party," says Larry Sabato, a political scientist at the University of Virginia in Charlottesville. "We all need to be patient and stop doing what comes naturally to media and pundits, trying to pull the curtain down before the play is finished."

Why the polls missed the mark

The day after New Hampshire, the big question was, what happened to Obama's lead over Clinton in the primary-eve polls – in some cases as big as 13 points? Mr. Sabato attributes the gap to "racial voting," the well-documented phenomenon in which voters tell pollsters they will vote for the black candidate, when in fact they will not. In this case, the exit poll showed Obama up by 5 points, but he ended up losing, 39 percent to 36 percent, with 99 percent of the vote counted.

Analysts also surmised that Clinton may have helped herself when she teared up at a campaign event on Monday – a display of emotion that got massive media attention and that may have helped counter her image as stoic and steely. Clinton and her husband, the former president, also may have helped her cause by arguing that she can be every much the "change agent" that Obama can – and that she is better equipped to deliver, given her more extensive experience.

"Words are not action," she said at the Democratic debate Saturday, acknowledging Obama's skill as an orator.

Women voters, in particular, may have been offended by the scene at the debate of Obama and the third-place New Hampshire finisher, former Sen. John Edwards, ganging up on Clinton. The former first lady wound up winning 46 percent of the Democratic women's vote in New Hampshire, versus 34 percent for Obama. Among voters 18 to 24 years old, Obama won 60 percent to Clinton's 22 percent.

The Democratic race is "a battle not only for the heart and soul of the party, but a battle over demographics – young versus old, men versus women," says independent pollster John Zogby. "It's not going to be pretty."

Clinton is well positioned to win Michigan, with its base of traditional Democrats and lower-income voters. However, the result there will be less meaningful for the Democrats, since their candidates are not campaigning in the state (because of a dispute over Michigan's decision to schedule the primary early). The odds are tougher to call in South Carolina. Obama's strong finishes in two overwhelmingly white states have muted early questions about his electability. Analysts say that African-Americans in the Palmetto State – half of the state's Democratic electorate and well aware of the historic nature of Obama's candidacy – are unlikely to stand in his way.

On GOP side, liabilities and 'angles'

In the Republican race, analysts say, all four leading candidates have liabilities. "But they each have some sort of angle where they could still pull it off," says David Kimball, a political scientist at the University of Missouri-St. Louis.

Mr. Giuliani had campaigned only half-heartedly in Iowa and New Hampshire, hoping for a rout on Feb. 5, when New York, California, and 20 other states vote. But the strategy may backfire, some analysts say. He has missed out on the crush of media coverage heaped on winners in the early-voting states. And as terrorism and war fade from television screens, his appeal as New York's mayor after 9/11 loses some luster.

A record 500,000 people – about 62 percent of registered voters – were estimated to have turned out at the polls on an unseasonably warm January day. For voters in both parties, the economy and the war in Iraq were top issues, according to exit polls.